Longitudinal propagation of a microwave beam in a laboratory plasma near the cyclotron resonance

A microwave beam (8-mm wavelength) was propagated parallel to the confining magnetic field in a plasma. To identify the transmission bands, the electron density and the magnetic field were slowly varied (in time) to separate the transmission bands of the left-hand circularly polarized wave from the right hand wave, above and below the electron cyclotron resonance. The experimental data show good agreement with the dispersion relations derived more than thirty years ago for ionospheric propagation.